Two day strikes on the Tube

London faces 48-hour strikes on the Tube in the most vicious escalation yet in the battle over train drivers' pay.

The two most powerful unions on London Underground, Aslef and the RMT, are to ballot more than 3,000 drivers who will be asked to endorse two-day stoppages.

The result - and the unions are certain to get an overwhelming endorsement in favour of industrial action - will be declared at the end of next month, meaning the stoppages could start a week or two later in March.

LU immediately condemned the move as both an " aggressive stance" and a "backward step" in industrial relations.

With the two unions combining the strikes it means the Tube, used by more than three million passengers a day, will be brought to a standstill. Besides causing horrific travel chaos throughout the capital, with roads blocked solid and hotels overbooked, London's businesses will lose tens of millions of pounds.

Maurice Fitzpatrick of Tenon, the professional services organisation, calculates that a single 24-hour stoppage of the Tube will cost business £45 million in lost output. The City Corporation puts the overall figure even higher, at up to £100 million.

Union leaders blamed LU management, accusing it of "reneging" on a pay deal drawn up in October. At issue is a demand by the two unions that the drivers of passenger trains, currently earning £29,000, should have their pay increased to the level of the drivers of engineering trains who earn more. An Aslef spokesman said: "There will be a ballot for strike action. We will be asking our members to support 48 hour stoppages. LU management has gone back on its word and must honour the agreement they signed last October."

Bob Crow, RMT assistant general secretary, added: "We are disappointed that after submitting our claim to mediation LU has failed to implement the mediator ' s recommendation to harmonise passenger and engineering train drivers' pay."

Paul Godier, LU managing director, said: "Today's decision by Aslef is a backward step. Where is the logic in Aslef balloting for strike action when we are still willing to talk and to offer a fair deal to our drivers? There is no need for Aslef to adopt such a negative, aggressive stance. Aslef need to understand our customers and staff deserve better."

The issue blew up last year when Tube strikes were only called off the day before they were due to begin. Within hours of the "deal" being signed there was a row over what had been agreed. Union leaders said they expected a £1,600 raise for passenger train drivers by this October. LU said it only agreed to "review alleged anomalies."